Year	% of cohort
1974	72.261848449707
1975	67.4714965820312
1976	73.5384292602539
1977	70.4626922607422
1978	70.5097503662109
1979	71.2418518066406
1980	75.3049468994141
1981	77.0828399658203
1982	66.0110473632812
1983	72.0205307006836
1984	74.543571472168
1985	77.6555099487305
1986	79.1886825561523
1987	79.8814010620117